# Water flowing through a 1.9-cm-diameter pipe can fill a 500L bathtub in 5.1min. What is the speed of the water in the pipe?

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1. area of pipe * speed of water = Q = flow volume/second

area = pi (.019)^2

volume = 0.5 m^3
time = 5.1*60 = 306
so

pi (.019)^2 V = .5 m^3/306 s
solve for V in m/s

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2. I did:
Q=change in v/change in t

= (500L)/(5.1m)
= (500L)/ (306s)
= 1.6 L/s

convert > 1 L = 100 mL = 10^3 cm^3 = 10^-3 m^3... therefore I got 16 x 10^-4

v= Q/A = Q/(pi)(r^2)
v = 16x10^-4/(pi)(0.0955)^2
= 0.017

i am incorrect though

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3. I get 1.45 m/s

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4. Re-tried using your help...

(pi)(0.19^2)V= 0.5m^3/306s

(pi)(0.19^2)V= 0.016

V= 0.016/(pi)(0.19^2)

V= 8 x 10^-4

... i was incorrect

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5. whoops I used diameter
use 4*1.45 = 5.8 m/s

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6. .5/306 = .00163, not .0163

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7. r = .019/2 = .0095
you have a decimal point off in the diameter too

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8. Just follow my way using the diameter and multiply by 4 at the end. A = pi d^2/4

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